The invention relates to biomaterials, and more particularly relates to electroactive biomaterials. In its most immediate sense, the invention relates to delivery of nerve growth factor to nerve tissue, and to implantable electroactive scaffolds used for such delivery.
When a peripheral nerve has a defect of more than two centimeters, a biomaterial is needed to repair the defect. This is conventionally done using either an autologous nerve graft (i.e. by taking a functioning section of a nerve from elsewhere in the patient's body) or using an allograft (i.e. by using a section of a nerve that has been removed from another living individual or from a cadaver). An autologous graft causes a loss of function from the site where the nerve section was removed, and an allograft is expensive. It would therefore be advantageous to provide a biomaterial having properties similar to an autologous nerve graft or a nerve allograft, so that the biomaterial could be used to repair peripheral nerve defects.
The invention proceeds from the realization that when a polymerizable electrically responsive unit such as pyrrole is anchored by polymerization within a polycaprolactone matrix in order to form an electroactive scaffold upon which cells can be cultured, the micro- and nano-topological features of the polycaprolactone matrix can be preserved. And, when pyrrole is so anchored within a polycaprolactone matrix, Schwann cells can be cultured on the scaffold. Schwann cells are known to increase the production of nerve growth factor when electrically stimulated, and nerve growth factor has been demonstrated to promote regeneration of nerve tissue. Hence, in accordance with the invention, nerve growth factor can be delivered to nerve tissue by implanting in the tissue a scaffold in accordance with the invention upon which Schwann cells have been cultured, and electrically stimulating the Schwann cells.
However, use of pyrrole is not essential to the practice of the invention. Another polymerizable unit can be used instead of pyrrole, provided the product is electrochemically responsive.
While the invention is motivated by the need to deliver nerve growth factor to repair nerve tissue, it can have other applications. Scaffolds in accordance with the invention can be used to deliver drugs, antibacterial agents, and antifungal agents. They can also be used as electroactive actuators capable of mechanotransduction of stem cells.